146 SPECIAL HISTOLOGY. 



changing the character which it possesses in man, the prepuce 

 takes on a highly glandular nature, and that even in man it 

 yields a secretion which differs considerably from common 

 epidermis. According to Lehmann, the yellow, fatty, strongly- 

 odorous preputial smegma of man contains, when dried, in 

 100 parts: Ethereal extract, 52 - 8; alcoholic extract, 7*4; 

 aqueous extract, 61 ; earthy salts, 9'7 ; albuminous substances 

 soluble in dilute acetic acid, 5*6 ; insoluble residuum, 18-5. The 

 ethereal extract contained saponifiable fat, cholesterin, a non- 

 saponifiable and uncrystallisable fat and bilin (Gallenstoff). 

 The smegma of the horse possessed nearly the same con- 

 stituents; and among the salts, oxalate of lime; while in man, 

 ammonio-phosphate of magnesia occurred. The watery extract 

 contained neither albumen nor casein. 



An extensive desquamation of the entire horny layer of 

 the epidermis, such as takes place in the embryo and in 

 many animals, does not occur in man except in certain morbid 

 states. On the other hand, its power of regeneration is 

 exhibited in other modes than those which have been mentioned. 

 Excised portions of the epidermis, for instance, are very readily 

 replaced, and with tolerable rapidity, so long as the corium is 

 not injured ; and, in fact, not by the immediate deposition of 

 epidermis in the wound, but only by the growing up of the 

 whole epidermis from below. If the corium be injured as well, 

 an epidermis is, indeed, formed upon the substance of the 

 cicatrix, but without any of the previous elevations and de- 

 pressions of the internal and external surface, because the new 

 corium has neither papillae nor ridges. If the epidermis be 

 raised up into a vesicle by acrid substances, e. g., Tartar 

 emetic, a slight burn, &c, the wall of the vesicle, which con- 

 sists of the horny layer and some few layers of cells of the 

 mucous layer, never again becomes adherent ; but from the 

 main substance of the mucous layer, which mostly remains lying 

 upon the papillae, a new horny layer is by degrees developed. 



If we inquire more minutely into the mode of regeneration 

 of the epidermis, there can, in the first place, be no doubt that 

 it takes place in the Malpighian layer, inasmuch as losses of 

 substance of the horny layer, e. g., a piece cut out, are restored 

 not by the formation of a new portion in the gap, but by the 

 growth outwards of a horny layer from below (the wound 



